Controlled release delivery system for nasal applications

ABSTRACT

This invention relates to a pernasally administrable preparation for the controlled release of sexual hormones to the systemic circulation, in particular to a formulation which enables its active ingredient to be absorbed in a sustained manner providing a better bioavailability at very low doses and longer duration of action.

FIELD OF THE INVENTION

The present invention relates to a formulation for the controlledrelease of sexual hormones to the systemic circulation after nasalapplication.

DESCRIPTION OF THE RELATED ART

Nasal drug delivery offers many advantages that include rapid adsorptiondue to abundant capillary vessels, fast onset of action, avoidance ofhepatic first-pass metabolism, utility for chronic medication and easeof administration.

It is known that, in contrast to large and/or ionized molecules,lipophilic pharmaceutical compounds having a sufficiently low molecularweight in general are readily adsorbed by the mucous membrane of thenose. For such drugs it is possible to obtain pharmacokinetic profilessimilar to those obtained after intravenous injection.

However, maintaining constant in vivo therapeutic drug concentrationsfor an extended period of time has been problematic because of the rapidmucociliary clearance of the therapeutic agent from the site ofdeposition resulting in a short span of time available for absorptionand of the presence of enzymes that may cause degradation in the nasalcavity.

A lot of efforts have been made to overcome these limitations includingthe use of bioadhesive systems that increase residence time in the nasalcavity, the use of enhancers to improve permeability of the nasalmembrane or the use of stabilizers that prevent degradation of drugs.

Thus in GB 1987000012176 the use of bioadhesive microspheres has beenproposed by Illum, and in PCT/GB98/01147 the use of in-situ gellingpectin formulations by WEST Pharmaceuticals.

Investigations on the nasal absorption of sexual steroids, rather smalland lipophilic compounds, have shown that they are readily absorbed bythe mucous membrane of the nose and are found very quickly in serum. Dueto this fact, to the short half-life of the compounds and to limitedpossibilities for formulating nasal application forms with sustainedrelease their use in clinical practice has been limited up to nowbecause hormone replacement therapy, in general, is a long-termapplication.

Several formulations were proposed for these drugs. Thus, in the case oftestosterone, which is nearly water-insoluble and somewhat better invegetable oil, Hussain et al., “Testosterone 17β-N,N-dimethylglycinatehydrochloride: A prodrug with a potential for nasal delivery oftestosterone”, J. Pharmaceut. Sci. 91(3): 785-789 (2002), concluded thatit would be an ideal candidate for nasal administration, if itssolubility in water could be increased. He proposed to use awater-soluble pro-drug, testosterone 17β-N,N-dimethylglycinate, andfound serum levels equal to intravenous administration with peak plasmaconcentrations within 12 min (25 mg dose) and 20 min (50 mg dose),respectively, and elimination half-lives of about 55 min. It must bementioned that this speed is not necessary/desirable because sex hormonereplacement is not an emergency therapy.

Ko et al., “Emulsion formulations of testosterone for nasaladministration”, J. Microencaps., 15(2): 197-205 (1998), proposed theuse of charged testosterone submicron 0/W emulsion formulations(water/Tween80, soybean oil/Span80) based on the hypothesis thatincreased absorption is possible upon solubilisation of the drug and/orprolongation of the formulation residence time in the nose. He found ahigher relative bioavailability of the positively (55%) and negatively(51%) charged emulsion compared to the neutral one (37%). Tmax wasobserved in every case at about 20 min after administration. It isdifficult to discuss these results because Ko did not take blood samplesbefore application and thus it is not possible to evaluate thedifferences in the decrease of serum levels, although from a graph itseems that after intravenous application (hydroalcoholic solution) thelevel shows the longest elimination half time. In practice, however,such an emulsion is not suitable because the droplet size (430 nm) isnot acceptable for nasal application.

The solubility of progesterone in water and oil is somewhat comparableto that of testosterone, but investigators have had differentapproaches:

Cicinelli et al., “Progesterone administration by nasal spray”, FertilSteril 56(1): 139-141 (1991), “Nasally-administered progesterone:comparison of ointment and spray formulations”, Maturitas 13(4): 313-317(1991), “Progesterone administration by nasal sprays in menopausalwomen: comparison between two different spray formulations”, GynecolEndocrinol 6(4): 247-251 (1992), “Effects of the repetitiveadministration of progesterone by nasal spray in postmenopausal women”,Fertil Steril, 60(6): 1020-1024 (1993) and “Nasal spray administrationof unmodified progesterone: evaluation of progesterone serum levels withthree different radioimmunoassay techniques”, Maturitas 19(1): 43-52(1994), showed that progesterone, dissolved in almond oil (20 mg/ml) andadministered by nasal spray, lead to higher bioavailability than thatprovided by progesterone dissolved in dimethicone or a PEG-basedointment. After nasal application of progesterone in almond oil Cmaxlevels were observed after 30 to 60 minutes, decreasing significantly 6to 8 hours after single administration.

Steege et al. “Bioavailability of nasally administered progesterone”,Fertil Steril, 46(4): 727-729 (1986), dissolved progesterone inpolyethylene glycol (200 mg/ml) and found Tmax at 30 min. The durationof serum levels was at least 8 hours but with high variations.

When progesterone was formulated in ethanol/propylene glycol/waterhowever Tmax was only 5.5 min (Kumar et al, “Pharmacokinetics ofprogesterone after its administration to ovariectomized rhesus monkeysby injection, infusion, or nasal spraying”, Proc. Natl. Acad. Sci.U.S.A., 79: 4185-9 (1982)).

Provasi et al., “Nasal delivery progesterone powder formulationscomparison with oral administration”, Boll. Chim. Farm. 132(10): 402-404(1993), investigated powder mixtures (co-ground and co-lyophilizedprogesterone/cyclodextrin) containing progesterone and also found Tmaxwithin 2-5 min and a serum level decrease already in about 20 min.

These results are quite similar to that found for testosterone (seeabove) and for an already marketed aqueous nasal spray containingestradiol, formulated in cyclodextrin (Aerodiol®). Maximum plasma levelsare reached within 10-30 minutes decreasing to 10% of the peak valueafter 2 hours already. Again, this speed is not necessary for sexhormone replacement therapy and not desirable in view of the shortelimination half-time of hormones.

Apart from the “liberation/adsorption” problem shown above, inconnection with sexual hormones and bioavailability, nearly exclusivelythe crucial liver metabolism and the short half-life are discussed,although a problem is also the high protein-binding. Approximately 40%of circulating plasma testosterone e.g. binds to sex hormone bindingglobulin (SHBG)—in men 2%, in women up to 3% remains unbound (free)—andthe remainder binds to albumin and other proteins. The fraction bound toalbumin dissociates easily and is presumed to be biologically active,whereas the SHBG fraction is not. The amount of SHBG in plasma howeverdetermines the distribution of testosterone in free and bound forms,where free testosterone concentrations determine (limit) the drug'shalf-life.

Accordingly, there is a constant need for a sexual hormone drugformulation system that is therapeutically effective when administeredto the nose of a patient and is safe, stable and easily manufactured.

SUMMARY OF THE INVENTION

The inventor made intensive studies of various sexual hormone drugformulations and, as a result, surprisingly found that the incorporationof the drug into a special lipophilic or partly lipophilic system notonly leads to a higher bioavailability in general caused by sustainedserum levels in plasma, but also to a more favourable serum levelprofile.

The invention comprises a formulation for nasal application comprisinga) at least one sexual hormone drug; b) at least one lipophilic orpartly lipophilic carrier; and c) a compound or a mixture of compoundshaving surface tension decreasing activity, an amount effective for insitu generation of an emulsion upon contact of the formulation withwater.

Preferably, the lipophilic carrier comprises an oil.

More preferably, said oil is a vegetable oil.

Most preferably, said oil is castor oil.

A preferred embodiment of the invention is characterized in that theamount of oil comprises between 30% and 98% by weight, preferablybetween 60 and 98% by weight, more preferably between 75% and 95% byweight, even more preferably between 85% and 95% by weight and mostpreferably around 90% by weight of the formulation.

A further embodiment is characterized in that component (c) comprises atleast one surfactant selected from the group consisting of lecithin,fatty acid ester of polyvalent alcohols, of sorbitanes, ofpolyoxyethylensorbitans, of polyoxyethylene, of sucrose, of polyglyceroland/or at least one humectant selected from the group consisting ofsorbitol, glycerine, polyethylene glycol, and macrogol glycerol fattyacid ester, or a mixture thereof.

Most preferably, component (c) comprises an oleoyl macrogoiglyceride ora mixture of oleoyl macrogoiglycerides.

Preferably, component (c) is comprised within the formulation in anamount of from 1 to 20% by weight, preferably 1 to 10% by weight, morepreferably 1 to 5% by weight, and most preferably at around 4% byweight.

A further embodiment comprises a viscosity regulating agent.

Preferably, it is preferred that said viscosity regulating agentcomprises a thickener or gelling agent selected from the groupconsisting of cellulose and cellulose derivatives, polysaccharides,carbomers, polyvinyl alcohol, povidone, colloidal silicon dioxide, cetylalcohols, stearic acid, beeswax, petrolatum, triglycerides and lanolin,or a mixture thereof.

Most preferably, said viscosity increasing agent is colloidal silicondioxide.

Preferably, the viscosity regulating agent is comprised within theformulation in an amount of from 0.5 to 10% by weight, preferably 0.5 to5% by weight, more preferably 1 to 3% by weight, and most preferably ataround 3% by weight.

In a preferred embodiment, the sexual hormone drug is testosterone.

Preferably, it is preferred that the sexual hormone drug is comprisedwithin the formulation in an amount of from 0.5 to 6% by weight,preferably 2 to 4% by weight, more preferably 0.5 to 2% by weight, andmost preferably at around 2% by weight.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 shows the serum levels of free testosterone at baseline and afternasal application of testosterone.

DETAILED DESCRIPTION OF THE INVENTION

The resultant formulation is chemically and physically stable and can bea suspension or a solution of the pharmacologically active substance.Preferably it is filled into a preservative-free, airless multi-dosedevice able to accurately deliver doses of the above formulation, alsoat higher viscosities.

Once at the absorption site, the drug or the drug particles should beefficiently trapped at the deposition site and be absorbed at apredictable rate across the mucous membrane of the patient, therebylimiting possible deactivation by metabolizing enzymes and/orprotein-binding.

As used herein the following terms are defined as follow:

The term “sexual hormone drug” shall mean at least one sexual hormone(such as testosterone) or at least one biologic pro-drug of a sexualhormone (such as androstenedione, progesterone,17-α-hydroxyprogesterone) or at least one derivative of a sexual hormone(such as mestanolone and 4-chloro-1-dehydromethyltestosterone) or acombination thereof. In a preferred embodiment the sexual hormone drugis testosterone.

The sexual hormone drug is comprised within the formulation in an amountof from 0.5 to 6% by weight, preferably 2 to 4% by weight, morepreferably 0.5 to 2% by weight, and most preferably at around 2% byweight

The drug of this invention may be introduced into the formulation alsoin a processed form such as microspheres, liposomes etc.

The term “lipophilic carrier” shall comprise, but not limited to, avegetable oil such as castor oil, soybean oil, sesame oil or peanut oil,fatty acid ester such as ethyl- and oleyloleat, isopropylmyristate,medium chain triglycerides, glycerol esters of fatty acids, orpolyethylene glycol, phospholipids, white soft paraffin, or hydrogenatedcastor oil. Particularly useful is castor oil.

The incorporation of the drug is also possible into an oil mixture.

The particular amount of oil that constitutes an effective amount isdependent on the particular viscosity regulating agent (see below) usedin the formulation. It is therefore not practical to enumerate specificamounts for use with specific formulations of the invention. Generally,however, the lipophilic part can be present in a formulation in anamount between 30% and 98% by weight, preferably between 60 and 98% byweight, more preferably between 75% and 95% by weight, even morepreferably between 85% and 95% by weight and most preferably around 90%by weight of the formulation.

Component (C) shall comprise at least a surfactant such as, but notlimited to, lecithin, fatty acid ester of polyvalent alcohols, ofsorbitanes, of polyoxyethylensorbitans, of polyoxyethylene, of sucrose,of polyglycerol and/or at least one humectant such as sorbitol,glycerine, polyethylene glycol, or macrogol glycerol fatty acid ester.Particularly useful, however, are oleoyl macrogolglycerides (such asLabrafil M 1944 CS, as available from Gattefossé (Franco)).

The incorporation of the drug is also possible into a surfactantmixture.

The particular amount of surfactant that constitutes an effective amountis dependent on the particular oil or oil mixture (see above) used inthe formulation. It is therefore not practical to enumerate specificamounts for use with specific formulations of the invention. Generally,however, the surfactant can be present in a formulation in an amount offrom 1 to 20% by weight, preferably 1 to 10% by weight, more preferably1 to 5% by weight, and most preferably at around 4% by weight.

The term “viscosity regulating agent” shall mean a thickener or gellingagent. Examples are, but not limited to, cellulose and derivativesthereof, polysaccharides, carbomers, polyvinyl alcohol, povidone,colloidal silicon dioxide, cetyl alcohols, stearic acid, beeswax,petrolatum, triglycerides or lanolin. Particularly useful however iscolloidal silicon dioxide (such as Acrosil 200, as available fromDegussa).

The incorporation of the drug is also possible into a mixture ofthickeners or gelling agents.

The particular amount of thickener/gelling agent that constitutes aneffective amount is dependent on the particular oil or oil mixture (seeabove) used in the formulation. It is therefore not practical toenumerate specific amounts for use with specific formulations of theinvention. Generally, however, the thickener/gelling agent(s) can bepresent in a formulation in an amount from 0.5 to 10% by weight,preferably 0.5 to 5% by weight, more preferably 1 to 3% by weight, andmost preferably at around 3% by weight.

The formulation according to this invention may also be processed intopowder form, e.g. by lyophilization or spray-drying.

Generally the formulations of the invention can be prepared very easilyby conventional methods, i.e.:

Emulsion

The thickener or gelling agent is added to a sufficient amount of waterand dispersed with high speed mixing and, if necessary, a surfactant(mixture 1). In a second container water and/or the lipophilic carrierare introduced and, if necessary, a surfactant (mixture 2). To mixture 2the hormone is added very carefully avoiding introducing air. Mixture 2is added to mixture 1, if necessary pH and tonicity are adjusted and thefinal mixture is homogenised and sterilised.

Water-Free Formulation

Lipophilic carrier and emulsifier are filled into a stirrer vessel andabout 75% of the viscosity regulating agent is mixed in. The hormone isadded under stirring until a homogenous dispersion of the activeingredient is obtained. Then the formulation is adjusted to thenecessary viscosity with the rest of the viscosity regulating agent.

The formulation is preferably filled into a preservative-free, airlessnasal spray device such as the COMOD system available from Ursatec.

By “higher availability” is meant that after a single application aserum level of sexual hormone significantly higher than baseline ismaintained for 6 hours, more preferably for 8 hours and most preferablyfor at least 10 hours.

Because sexual hormones are nearly not soluble in water liberation fromthe formulation is the speed-limiting step for adsorption. It has beensurprisingly found that the incorporation of a sexual hormone drug suchas testosterone in an oily formulation containing a suitable surfactantaccording to the invention leads of to physiologic serum levels and to asteady, sustained action of the hormone over time.

On one hand, the release of the hormone is sustained due to itssolubility in the oily carrier and to the viscosity of the formulationremaining on the mucous membrane for a prolonged duration of time.

On the other hand, upon contact of the formulation with the humidity ofthe mucous membrane the drug's precipitation is hindered by thesurfactant's property to form oil drops containing the drug. Thus byadding a suitable surfactant to the formulation the dissolution patternof the hormone becomes more favourable and effective because there is nobig variability in dissolution ensuring bioequivalence.

EXAMPLE

Typical Formulation

The formulation shown below was selected considering the serum level ofthe active ingredient achieved but it also exhibits a skin care propertywhich is important for long term applications.

TABLE 1 Most preferred formulation Compound Amount per containerDelivery per spray Testosterone 2% ≈2.8 mg Aerosil ® 200 3% ≈4.2 mgLabrafil ® M 1944 CS 4% ≈5.6 mg Castor oil, refined grade 91%  ≈127.4mg 

Typical Serum Level

Comparing different formulations (see FIG. 1) containing testosterone itis obvious that Cmax is clearly decreased in the special oilyformulation of this invention, which is desirable in view oftoxicological considerations. Further the level of unbound testosteroneis very constant over at least 10 hours mimicking the physiologic dailyrhythm of testosterone release.

The dotted line shows the serum level after application of 1 spray pernostril once of the most preferred formulation (see Table 1).

It can be concluded that the formulation for nasal application of thisinvention is different from conventional formulations, especially tothose for sustained release, as it is mimicking the physiologic dailyrhythm of testosterone release. It is also avoiding supra- andsub-normal testosterone levels, which is pleasant for the patient and ademand for hormone replacement therapy. As shown in FIG. 1 (upper line),a simple nasal spray containing testosterone is unsatisfactory in thissense.

The features disclosed in the foregoing description, in the claimsand/or in the drawings may, both separately and in any combinationthereof, be material for realising the invention in diverse formsthereof.

1.-14. (canceled)
 15. A testosterone gel formulation for nasaladministration comprising: (a) testosterone; (b) at least one lipophilicor partly lipophilic carrier; and (c) a compound or a mixture ofcompounds having surface tension decreasing activity.
 16. Thetestosterone gel formulation according to claim 15, wherein saidlipophilic carrier comprises an oil.
 17. The testosterone gelformulation according to claim 16, wherein said oil is a vegetable oil.18. The testosterone gel formulation according to claim 17, wherein saidvegetable oil is castor oil.
 19. The testosterone gel formulationaccording to claim 18, wherein the castor oil is hydrogenated.
 20. Thetestosterone gel formulation according to claim 17, wherein saidvegetable oil is soybean oil.
 21. The testosterone gel formulationaccording to claim 17, wherein said vegetable oil is sesame oil.
 22. Thetestosterone gel formulation according to claim 17, wherein saidvegetable oil is peanut oil.
 23. The testosterone gel formulationaccording to claim 16, wherein said lipophilic carrier comprises an oilmixture.
 24. The testosterone gel formulation according to claim 16,wherein the oil is present in the testosterone gel formulation in anamount of from about 30% to about 98% by weight of the testosterone gelformulation.
 25. The testosterone gel formulation according to claim 15,wherein the lipophilic carrier comprises a fatty acid ester.
 26. Thetestosterone gel formulation according to claim 25, wherein the fattyacid ester is ethyloleat.
 27. The testosterone gel formulation accordingto claim 25, where the fatty acid ester is oleyloleat.
 28. Thetestosterone gel formulation according to claim 15, wherein thelipophilic carrier comprises isopropylmyristate.
 29. The testosteronegel formulation according to claim 15, wherein the lipophilic carriercomprises medium chain triglycerides.
 30. The testosterone gelformulation according to claim 15, wherein the lipophilic carriercomprises glycerol esters of fatty acids.
 31. The testosterone gelformulation according to claim 15, wherein the lipophilic carriercomprises polyethylene glycol.
 32. The testosterone gel formulationaccording to claim 15, wherein the lipophilic carrier comprisesphospholipids.
 33. The testosterone gel formulation according to claim15, wherein the lipophilic carrier comprises white soft paraffin. 34.The testosterone gel formulation according to claim 15, wherein saidcompound or said mixture of compounds having surface tension decreasingactivity comprise (a) at least one surfactant selected from the groupconsisting of lecithin, a fatty acid ester and mixtures thereof, (b) atleast one humectant, and (c) mixtures thereof.
 35. The testosterone gelformulation according to claim 34, wherein said compound or said mixtureof compounds having surface tension decreasing activity comprise anoleoyl macrogolglyceride or a mixture of oleoyl macrogolglycerides. 36.The testosterone gel formulation according to claim 34, wherein saidcompound or said mixture of compounds having surface tension decreasingactivity is comprised within the formulation in an amount from about 1%to about 20% by weight.
 37. The testosterone gel formulation accordingto claim 15, further comprising a viscosity regulating agent.
 38. Thetestosterone gel formulation according to claim 37, wherein theviscosity regulating agent comprises a thickener or gelling agentselected from the group consisting of cellulose and cellulosederivatives, polysaccharides, carbomers, polyvinyl alcohol, povidone,colloidal silicon dioxide, cetyl alcohols, stearic acid, beeswax,petrolatum, triglycerides, lanolin and mixtures thereof.
 39. Thetestosterone gel formulation according to claim 37, wherein theviscosity regulating agent is colloidal silicon dioxide.
 40. Thetestosterone gel formulation according to claim 37, wherein theviscosity regulating agent is present within the testosterone gelformulation in an amount of from about 0.5% to about 10% by weight ofthe testosterone gel formulation.
 41. The testosterone gel formulationaccording to claim 15, wherein said testosterone is present within thetestosterone gel formulation in an amount of from about 0.5% to about 6%by weight of the testosterone gel formulation.
 42. The testosterone gelformulation according to claim 15, wherein said testosterone isintroduced into the formulation in the form of microspheres.
 43. Thetestosterone gel formulation according to claim 15, wherein saidtestosterone is introduced into the formulation in the form ofliposomes.
 44. The testosterone gel formulation according to claim 15,wherein the formulation provides for the controlled release oftestosterone after nasal application.
 45. The testosterone gelformulation according to claim 15, wherein the formulation provides forsustained serum levels of testosterone following nasal administration.46. The testosterone gel formulation according to claim 45, wherein saidtestosterone is maintained at a serum level greater than baseline for atleast about 6 hours following nasal administration.
 47. The testosteronegel formulation according to claim 46, wherein said testosterone serumlevel is achieved after one application per nostril of the testosteronegel formulation.
 48. The testosterone gel formulation according to claim47, wherein the serum level of unbound testosterone is similar to thephysiologic daily rhythm of testosterone release.
 49. A method oftestosterone replacement therapy comprising administering thetestosterone gel formulation of claim 15 to the nasal mucosa.
 50. Themethod of claim 49, wherein the testosterone gel formulation is providedin a device capable of delivering multiple, individual doses of thetestosterone gel formulation.
 51. The method of claim 49, wherein thetestosterone gel formulation provides for the controlled release oftestosterone into the systemic circulation and/or the brain after nasalapplication.
 52. The method of claim 51, wherein the testosterone gelformulation provides for sustained serum levels of testosterone.
 53. Themethod of claim 52, wherein said testosterone is maintained at a serumlevel greater than baseline for at least about 6 hours after nasaladministration.
 54. The method of claim 53, wherein the serum level isachieved after one application of the testosterone gel formulation pernostril.
 55. The method of claim 54, wherein the serum level of unboundtestosterone is similar to the physiologic daily rhythm of testosteronerelease.
 56. The testosterone gel formulation according to claim 16,wherein the oil is present in the testosterone gel formulation in anamount of from about 60% to about 98% by weight of the testosterone gelformulation.
 57. The testosterone gel formulation according to claim 16,wherein the oil is present in the testosterone gel formulation in anamount of from about 75% to about 95% by weight of the testosterone gelformulation.
 58. The testosterone gel formulation according to claim 16,wherein the oil is present in the testosterone gel formulation in anamount of from about 85% to about 95% by weight of the testosterone gelformulation.
 59. The testosterone gel formulation according to claim 16,wherein the oil is present in the testosterone gel formulation in anamount of from about 90% by weight of the testosterone gel formulation.60. The testosterone gel formulation according to claim 37, wherein theviscosity regulating agent is present within the testosterone gelformulation in an amount of from about 0.5% to about 5% by weight of thetestosterone gel formulation.
 61. The testosterone gel formulationaccording to claim 37, wherein the viscosity regulating agent is presentwithin the testosterone gel formulation in an amount of from about 1% toabout 3% by weight of the testosterone gel formulation.
 62. Thetestosterone gel formulation according to claim 37, wherein theviscosity regulating agent is present within the testosterone gelformulation in an amount of from about 3% by weight of the testosteronegel formulation.
 63. The testosterone gel formulation according to claim15, wherein said testosterone is present within the testosterone gelformulation in an amount of from about 2% to about 4% by weight of thetestosterone gel formulation.
 64. The testosterone gel formulationaccording to claim 15, wherein said testosterone is present within thetestosterone gel formulation in an amount of from about 0.5% to about 2%by weight of the testosterone gel formulation.
 65. The testosterone gelformulation according to claim 15, wherein said testosterone is presentwithin the testosterone gel formulation in an amount of about 2% byweight of the testosterone gel formulation.
 66. The testosterone gelformulation according to claim 45, wherein said testosterone ismaintained at a serum level greater than baseline for at least about 8hours after nasal administration.
 67. The testosterone gel formulationaccording to claim 45, wherein said testosterone is maintained at aserum level greater than baseline for at least about 10 hours afternasal administration.
 68. The testosterone gel formulation according toclaim 52, wherein said testosterone is maintained at a serum levelgreater than baseline for at least about 8 hours after nasaladministration.
 69. The testosterone gel formulation according to claim52, wherein said testosterone is maintained at a serum level greaterthan baseline for at least about 10 hours after nasal administration.70. The testosterone gel formulation according to claim 34, wherein saidcompound or said mixture of compounds having surface tension decreasingactivity is comprised within the formulation in an amount from about 1%to about 10% by weight.
 71. The testosterone gel formulation accordingto claim 34, wherein said compound or said mixture of compounds havingsurface tension decreasing activity is comprised within the formulationin an amount from about 1% to about 5% by weight.
 72. The testosteronegel formulation according to claim 34, wherein said compound or saidmixture of compounds having surface tension decreasing activity iscomprised within the formulation in an amount of about 4% by weight.